Expression of TFE3 in Cellular and Myxoid Type of Neurothekeoma: Four Cases in Young Children and Adolescents.

Introduction: Cellular neurothekeoma is a benign tumor that mainly occurs in young children and adolescents. The aberrant expression of transcription factor E3 (TFE3) has not been reported in cellular neurothekeoma previously. Case report: We report four cellular neurothekeoma with aberrant immunohistochemical expression of TFE3 protein. The fluorescence in situ hybridization (FISH) showed no TFE3 gene rearrangement or amplification. Discussion/Conclusion: TEF3 protein expression may not be related to TFE3 gene translocation in cellular neurothekeoma. TFE3 may be a potential pitfall in diagnosis, for several malignant tumors in children also express TFE3. The aberrant expression of TFE3 may offer insights into cellular neurothekeoma etiology, and associated molecular mechanisms.

Cellular neurothekeoma occurring at the site of radiation therapy in a child with medulloblastoma.

Cellular neurothekeoma is a rare, benign cutaneous neoplasm. We report a case of cellular neurothekeoma arising on the mid-back of a 10-year-old boy within the previous radiation therapy field for medulloblastoma. Clinical features of cellular neurothekeoma in children are similar to those in adults, except that there have been no reports of local recurrence in children following surgical excision, and the presence of atypical histological features does not predict clinical behavior. Recognition of this entity in children is important to avoid misdiagnosis and overly aggressive treatments.

Multiple myxoid cellular neurothekeomas in a patient with systemic lupus erythematosus.

Cellular neurothekeoma is a cutaneous tumor with a distinctive histopathologic appearance characterized by a dermal-based multinodular proliferation of epithelioid to spindled cells. Although the tumor may show varying amounts of myxoid stroma, extensive myxoid change is uncommon. The tumor typically presents as a solitary nodule with a predilection for the head and neck and upper limbs; examples of multiple cellular neurothekeomas are decidedly rare. The present report describes a unique case of multiple myxoid cellular neurothekeomas arising in a 60-year-old female with systemic lupus erythematosus. Two papular lesions were identified involving the skin inferior to the umbilicus and the left inguinal crease. Both lesions were histopathologically similar, forming a nodular mass composed of epithelioid cells in a prominent myxoid stroma. By immunohistochemistry the lesional cells expressed NKI/C3, microphthalmia transcription factor (MiTF), and CD68, with focal staining for PGP9.5, factor XIIIa, and CD10 also observed. The tumors were negative for S-100, SOX-10, epithelial membrane antigen, desmin, smooth muscle actin, glial fibrillary acid protein, and CD34. The present case confirms that cellular neurothekeoma can present clinically as multiple lesions and can have a predominantly myxoid appearance, potentially mimicking other cutaneous myxoid lesions.

Atypical cellular neurothekeoma (ACN) of the elderly: case report and brief review of the literature.

Atypical cellular neurothekeoma (ACN) is an aggressive and rare variant of cellular neurothekeoma. Only few cases have been reported in the literature and the biological behavior seems to be uncertain. We describe the case of an ACN presenting on the scalp of an elderly man, emphasizing the cytologic features of malignancy. In addition, we provide a brief overview of the literature and discuss the differential diagnosis with other entities, and the possible diagnostic pitfalls.

Multiple cellular neurothekeomas in a middle-aged woman including the lower extremity: A case report and review of the current literature.

Cellular neurothekeoma is a benign cutaneous neoplasm that typically occurs on the head, neck, and upper body of young adults with a slight female predominance. It is a rare lesion to diagnose and multiple neurothekeomas in one patient are even more uncommon finding. We present a case of multiple neurothekeomas in a middle-aged woman with lower extremity involvement and summarize the current literature on multiple neurothekeoma patients. A 46-year-old female presented with nearly one dozen skin-colored papules on the head, upper limb, and lower limb. The lesions were clinically diagnosed as dermatofibromas and a nevus. Eight lesions were biopsied and confirmed to be cellular neurothekeomas, with one initially misinterpreted on histology as a dermatofibroma. Awareness of cellular neurothekeoma as a diagnostic entity and the possibility of atypical presentations as seen in our case (eg, in multiple numbers, in older adults, and on the lower extremity) are important in allowing for accurate clinical and histological diagnosis of these lesions. The possibility of a syndromic association with multiple cellular neurothekeomas should be explored further.

Cellular neurothekeoma: Report of two cases with unusual immunohistochemical features.

Cellular neurothekeoma (CNT) is a dermal lesion with still unknown histogenesis, characterized by immunohistochemical staining for NKI/C3, NSE, MiTF, CD10 and CD68, whereas S100 protein, desmin and cytokeratins are negative. Particularly, in several studies NKI/C3 has been reported as a strong marker of CNT. We describe herein the clinical, histopathological and immunohistochemical features of two cases morphologically consistent with myxoid CNT, one of which showing some atypical features, both characterized by negative immunohistochemical staining for NKI/C3. Our findings stress the importance of morphology in diagnosing CNT and underline the fact that NKI/C3 can fail to stain cases belonging to the "neurothekeoma family." In selected cases of CNT, an expanded immunohistochemical panel is mandatory to differentiate this tumor from other dermal lesions.

Atypical cellular neurothekeoma: A potential diagnostic pitfall for benign and malignant spindle cell lesions in skin.

Cellular neurothekeomas (CNTs) are rare, benign cutaneous tumors that arise primarily on the head and neck, with a slight female predominance. CNTs with atypical features have been described, including those with an infiltrative growth pattern. Although CNTs with atypical features are benign, recognition of this entity can pose diagnostic challenges. Here, we report a case of CNT with an unusual clinical presentation on the left second digit, and with atypical histological features including an infiltrative growth pattern, which could have been mistaken for features of malignancy.

Benign Nerve Sheath Myxoma in an Infant Misdiagnosed as Infantile Digital Fibromatosis.

Herein we present the case of a 16-month boy, clinically diagnosed with infantile digital fibromatosis, but 9 months after continued growth, the mass was excised and the histopathologic diagnosis was that of a benign nerve sheath myxoma. We present this case to emphasize that nerve sheath myxomas (also known as myxoid neurothekeoma) should be included in the differential diagnosis of dermal nodules in infants.

An unusual case of neurothekeoma of the arm in an adult.

Neurothekeomas are uncommon benign neoplasms with a peripheral nerve sheath origin. This tumor usually involves dermis and is described as a small, solitary, slow growing and reddish to flesh-colored nodule or papule. Neurothekeoma preferentially affects the central aspect of the face, the arms or shoulders of women in the second and third decades of life. This is the first case report of neurothekeoma involving the wrist developing from synovial tissue and with uncertain clinical behavior in an adult female. The tumor was completely excised under brachial plexus block. Histopathologically, the examination of the microscopic slides revealed the presence of a 20-mm diameter, well-circumscribed and multilobulated tumor composed of abundant myxoid stroma with cellular elements; with immunohistochemistry there was positivity to vimentin but S100-protein, epithelial membrane antigen, cytokeratin AE1-3, CD99 and CD34 were all negative. This pattern suggested a myxoid tumor form of neurothekeoma, mixed subtype. The patient had an atypical local recurrence and was re-operated after 3 months. After 12 months there was no evidence of clinical recurrences confirmed by magnetic resonance evaluation. Basically, our case report adds an important element in the correct clinical management of neurotecheomas: faced with a histological diagnosis with an unusual localization and mixed or hypercellular type, clinicians must consider the possibility of an early local recurrence, suggesting a close clinical and radiological follow-up.

Immunohistochemical analysis of KBA.62 in 18 neurothekeomas: a potential marker for differentiating neurothekeoma, but a marker that may lead to confusion with melanocytic tumors.

BACKGROUND: Neurothekeoma represents a neoplasm of uncertain histogenesis that often occurs on the head and neck of younger individuals. Distinguishing neurothekeoma from other tumors, particularly malignancies such as melanoma, can be difficult given the variable presence of nuclear atypia, mitoses and extension into fat or skeletal muscle. KBA.62 represents an anti-melanoma monoclonal antibody that marks approximately 93% of melanomas. This study sought to evaluate KBA.62 expression in neurothekeomas, both as means of affirming the diagnosis and as a potential confounding factor in excluding a melanocytic process. METHODS: Eighteen neurothekeomas from 17 patients were analyzed by light microscopy and immunohistochemistry. Immunohistochemistry was performed with KBA.62, S100 and CD10 antibodies. The diagnosis of neurothekeoma was confirmed by at least two dermatopathologists. RESULTS: All cases showed similar light microscopic and immunohistochemical features. With the exception of two cases, cells expressed CD10 and exhibited morphologic features consistent with neurothekeoma. All 18 cases were S100 immunonegative. The epithelioid cells of all neurothekeomas were KBA.62 immunopositive, including both of two neurothekeomas occurring in the same patient. CONCLUSIONS: In this study 100% of neurothekeomas tested were KBA.62 positive, admittedly to varying degrees, suggesting the utility of this reagent as being supportive of the diagnosis of neurothekeoma.

Cellular neurothekeoma of the eyelid: a unique internal palpebral presentation.

A 50-year-old woman presented with a mass lesion of the inferolateral palpebral conjunctiva similar in appearance to a chalazion, but unusual enough in presentation that excisional biopsy was initially performed. Histopathologic analysis revealed a dermal fibrohistiocytic neoplasm consistent with cellular neurothekeoma. Neurothekeoma is a benign tumor; the cellular variant is rare and of unclear histogenesis. Completely internal eyelid location is particularly rare, with other identifiable case reports of cellular neurothekeoma palpebrae referring to external or unspecified eyelid location. This case provides an example of the chalazion as masquerader and re-emphasizes the importance of maintaining a broad differential diagnosis and high index of suspicion regarding atypically appearing chalazia.

Erythematous nodular lesion on the chest of an infant.

An 11-month-old girl presented with an erythematous nodule on the chest, which had been growing for 8 months. The tumor was composed of uniform polygonal and spindle-shaped cells, forming nodules and fascicles. The diagnosis of neurothekeoma was based upon the histology and immunohistochemistry.

[Nerve sheath myxoma of the hyponychium]. / Myxome des gaines nerveuses de l'hyponychium.

BACKGROUND: Nerve sheath myxoma is a rare benign tumour of the extremities that was long confounded with neurothekeoma. Herein, we describe a rare case of interest because of its site on the hyponychium. PATIENTS AND METHODS: A 31-year-old woman presented with a painless distal tumour on the right ring finger that had been present for 3 to 4 years. It consisted of a firm, round nodule under the nail and spreading to the fingertip. Complete excision was carried out after cutting away the distal nail plate. Histological examination revealed a myxoid tumour comprising very clearly delineated lobules containing pale fusiform cells with small nuclear inclusions. These cells expressed S100 protein but no CD34 or epithelial membrane antigen (EMA). Complete excision was performed and a full recovery was made. DISCUSSION: This type of tumour is characteristic of nerve sheath myxoma, and is almost certainly of Schwannian origin, although distinct from Schwannoma. It is rare, occurs after the age of 35 years and is preferentially located in the extremities of the limbs. There has only been one other description of its occurrence under the fingernail, in which it was described as neurothekeoma. However, neurothekeoma is entirely different, being more cellular, with no expression of protein S100, and marked by the NKIC3 antibody; it occurs in children or young adults, and is frequently found on the face. These two tumours were confused for some time, but today they must be completely distinguished from one another. These myxomas must be completely excised because of the risk of relapse. Finally, they should be distinguished from other myxoid tumours of the digits, certain of which can be malignant.

[A case of primary cutaneous PEComa]. / Un PECome cutané primitif.

BACKGROUND: PEComas (PEC: Perivascular epithelioid cell) are tumours expressing both melanocytic and myogenic markers. The clinical features are non-specific. PATIENTS AND METHODS: A 55-year-old woman presented with a non-specific tumour on her right arm. Histological examination revealed an intradermal tumour composed of clear epithelial cells. The tumour was positive for HMB45 and protein S100, and was negative for Melan-A and actin. A diagnosis of PEComa was retained despite negative myogenic markers. DISCUSSION: PEComas are neoplasms composed of nests and fascicles of clear to granular epithelioid cells that express both melanocytic markers (HMB45, Melan-A, NK1C3, tyrosinase) and myogenic markers (actin, caldesmin, desmin, calponin), whereas S100 protein and cytokeratins are usually absent. Included in this broad category are angiomyolipoma, clear-cell "sugar" tumours and lymphangioleiomyoma. Some deep PEComas may have a malignant course. Cutaneous primitive forms are exceptional and often benign. Histological differential diagnoses to consider are those of clear-cell tumours: paraganglioma-like dermal melanocytic tumour, melanoma, metastatic clear-cell renal carcinoma and epithelioid sarcoma. In our patient, a diagnosis of cutaneous primitive PEComa was retained despite the absence of myogenic markers and the positivity of the protein S100, based on the cytological and immunohistochemical features, which were not evocative of any other diagnosis. CONCLUSION: Cutaneous PEComa are non-specific tumours. Histological analysis confirms the diagnosis and allows other more aggressive tumours to be ruled out.

Expression of MiTF may be helpful in differentiating cellular neurothekeoma from plexiform fibrohistiocytic tumor (histiocytoid predominant) in a partial biopsy specimen.

BACKGROUND: Overlapping histopathologic features of cellular neurothekeoma (CNT) and plexiform fibrohistiocytic tumor (PFHT), when both are predominantly composed of histiocytoid cells, make distinction between these entities challenging. Some have suggested that CNT and PFHT are related entities. No prior study has demonstrated a reliable immunohistochemical panel to differentiate these entities. METHODS: Skin biopsies diagnosed as CNT and PFHT, from 2004 to 2010 were retrieved with accompanying pathology reports. Each case was reviewed by at least 2 dermatopathologists and 2 soft tissue pathologists for confirmation of diagnosis. All cases were then evaluated for immunohistochemical expression of PAX2, NKIC3, CD10, and microphthalmia transcription factor (MiTF). RESULTS: Histopathologically, the histiocytoid areas of each tumor shared similar architecture, demonstrating nests and fascicles of histiocytoid to spindled cells, with some separation of nests by collagen bands. Both CNT and PFHT were uniformly positive for NKIC3 and CD10, and both were frequently PAX2 positive. MiTF was strongly and diffusely positive in CNT and was consistently negative in the PFHT. CONCLUSIONS: CNT and PFHT share many histopathologic features and immunohistochemical staining patterns. Of the stains we evaluated, we found that expression of MiTF may be a reliable marker for distinguishing CNT from histiocytoid-predominant PFHT, especially in instances where only a small part of the tumor is sampled for evaluation.

A myxoid neurothekeoma of the nose.

Neurothekeoma is a rare neoplasm assigned to the broad category of benign peripheral nerve sheath tumors. Its cell of origin is still unknown, but most ultrastructural and immunohistochemical studies have favoured the Schwann cell perineurium or fibroblast. Neurothekeoma most commonly presents in females, especially in the second and third decades of life. Typically it presents as an asymptomatic solitary, firm, flesh-coloured or hyperpigmented slow-growing papule or nodule that involves the skin and superficial subcutis. It usually involves the face, neck, arm or shoulder but can also involve extracutaneous sites. Neurothekeoma occurs in myxoid (classic), cellular and intermediate (mixed) variants. Here, we report a 45-year-old male patient presenting with a nodule on the nose that was found to be a myxoid variant of neurothekeoma. It was treated with a simple shave excision followed by removal of the lobulated deeper part by forceps. He had no recurrence after three years of follow-up. To the best of our knowledge, this is the first case of a myxoid neurothekeoma of the nose to be reported in the Middle East.

Neurothekeoma of the median nerve: case report.

We report the case of a large intraneural neurothekeoma of the median nerve at the wrist. Neurothekeomas are rare; they are small, superficial, and typically asymptomatic benign tumors of undetermined cellular origin. Complete excision is usually curative. This case is interesting owing to the tumor's large size and location within the median nerve, which made it highly symptomatic, mimicking carpal tunnel syndrome.

Alar rim neurothekeoma in a child.

OBJECTIVE: We report on the case of an 11-year-old girl with atypical neurothekeoma of the left lateral alar rim that was excised and ultimately closed primarily after an unsuccessful attempt at reconstruction with a full-thickness auricular composite graft. METHODS: In this case report, we present a description of the case and a review of the literature. RESULTS: The patient underwent successful excision of neurothekeoma and subsequent auricular cartilage graft reconstruction. Reconstruction failed to adequately heal at several months postoperatively and the defect was closed primarily. CONCLUSIONS: Rapidly growing nodules of the nose can have a broad differential and requires pathological diagnosis via early biopsy. This is important because the surgical approach varies depending on the lesion and its potential for metastasis and local growth.